JPH0230434A - Method for discharge process - Google Patents

Abstract

PURPOSE:To get rid of a blockage due to a processing chip, in order to execute a stable discharge process, by minimizing the size of the processing chip on its second circuit, using an electrode part composed of a pair of electrodes having a stage part of a certain shape. CONSTITUTION:Being held by a dividing device, a material 4 is divided at a pitch of 2xn (n is an integer) of a turn blade for its processing position, 2 circulated. At the processing position, the material 4 is discharge-processed by an electrode part that is composed of a pair of electrodes 1 which have a stage in a shape determined based on a wing bottom interval, wing point width, length and thickness of the material 4, and blades are formed in the order of 11a, 11c, 11b,...11n-1, 11n. By using the electrode 1 with a stage such as this, the material 4 can be discharge-procesed with a good stability, through minimization of the size of a processing chip generated from a blank 4a during the process in a second circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for electrical discharge machining of a workpiece such as a turbine blade in which blades are formed radially around an axis.

[Prior Art] FIG. 3 is a schematic diagram showing the overall configuration of an apparatus for electrical discharge machining of a normal turbine blade. In the figure, ('') is the electrode, (2) is the holder that fixes the electrode (1), (3) is the main shaft that moves the electrode (1) up and down, (4) is the material of the turbine blade, and (5) is this An indexing device that supports the material (4) and determines the processing position, (6) is a processing tank, (7) is a processing liquid,
(8) is a power source that applies a pulse voltage between the electrode (1) and the material (4).

FIG. 4 is an explanatory diagram showing the names of each part of the blade processed into a predetermined shape, and in figures (a) and (b),
(11) is a blade, and (12) is an interwing part. (c)
The figure is a view in the direction of arrow A in figure (a), and (13) is the width between the bases of the wings;
(14) is the area between the blade tips, (15) is the blade thickness, (1
6) shows the part between the blade bottoms, and (17) shows the part between the blade tips.

Fig. 5 is a front view and a side view showing the shape of a pair of electrodes (1) fixed to a holder (2), and (21) is a discharge gap when machining the thickness (15) of the blade (11). This is a spacer whose thickness is determined taking g into consideration.

The electrode part having the above shape is attached to the main shaft (3) in Fig. 3, and the material (4) supported by the indexing device (4) is indexed every two pitches of the blade (11) and rotated twice. move it,
Electrical discharge machining is performed by the electrode (1) as the main shaft (3) moves up and down. In this process, if the play of the blade part (12) is more than twice the blade tip amount line (14) shown in Fig. 4 or the blade base width (13), the index During the second round of machining with the device (5), the unprocessed chip (22) as shown by the shaded area in Fig. 6 is left unprocessed, and the electrode <1
If the electrode (]) digs into the electrode (1) side just before it reaches point B in the figure with the machining feed, the machining will become unstable and the machining may have to be interrupted.

In order to prevent the above-mentioned unstable machining, Fig. 7(a) to (
As shown in C), align the center of the interwing part (12) with the center of the pre-processing electrode (24), and insert the indexing device (5) into the material (4) every two pitches of the blade (11). ) to form the pre-processed groove (25), and then the holder (2)
7(d) by a pair of electrodes (1) supported by
As shown in ~(f), processing is performed while rotating the material (4) every two pitches of the blade (11), so that the blade (11) is formed over the entire circumference.

[Problem to be solved by the invention] In the conventional electric discharge machining method for a turbine plate as described above, it is possible to prevent unstable machining due to biting of the unmachined tip (22) into the electrode (1). In order to
), the machining time becomes long, and electric discharge machines without an automatic electrode exchange device have problems such as interruption of machining and inability to operate automatically.

This invention was made to solve the above-mentioned problems. Stable machining can be performed using one type of electrode, thereby making it possible to shorten machining time and ensuring reliable automatic operation. The purpose is to obtain an electric discharge machining method that can be used.

[Means for Solving the Problems] The electric discharge machining method according to the present invention changes the shape of a pair of symmetrically opposed electrodes supported by a holder by adjusting the width between the bases of a turbine blade or the like, the width of the blade tip, and the like. It is determined to form a stepped portion based on the thickness, and an indexing device is used to index the cumulative moon every two pitches of a turbine blade or the like and rotate it twice,
It is designed to be processed using an electrode section.

[Function] In this invention, the thickness of the electrode forming the stepped portion is based on the width between the blade bases and the blade tip width to minimize the size of the machining chips generated during the second round of machining. Stable machining can be performed without interference from machining chips.

[Example 1] FIG. 1 is a front view and a side view showing an electrode structure used to carry out the electrical discharge machining method according to the present invention. In the figure, (1) is a pair of electrodes fixed to the holder (2) in a symmetrical shape, and (21) is the discharge gap during machining, which corresponds to the thickness (15) of the blade (11) shown in Figure 4. This is a spacer whose thickness t is determined taking g into account. The thickness tl of the tip of the electrode (1) is a little more than 1/2 of the width between the blade bases (13) shown in Fig. 4, and the thickness t2 of the fixed part side is also a little more than 172 of the blade tip amount line (14). defined, length Ω and thickness 1. 1 to form a stepped portion, and the 0 point of this stepped portion is determined so as not to interfere with the surface of the adjacent blade (II) during processing to be described later.

Attach the electrode part shaped as above to the main shaft (3) in Fig. 3, and as in the conventional example, insert the material (4) supported by the indexing device (4) into two pitches of the blade (]1). Each index is rotated twice, and electric discharge machining is performed using the electrode (1) as the main shaft (3) moves up and down each time it is indexed.

FIG. 2 is an explanatory diagram showing the process of forming the blade (11) by this electric discharge machining. First, as shown in Figure (a), at the first indexing, the first blade (lla) is formed by machining to a predetermined depth by the electric discharge generated between the electrode (1) and the material (4). Then, as shown in figure (b), the indexing device (5) rotates the material (4) two pitches clockwise as viewed from the figure, and the blade is at the third position from the blade (1, 1a). Machining (lie) forms a blank (4a) in which the blade (llb) between blade (1], a) and blade (He) is machined. Continue machining in the same way, and as shown in figure (e), machining the blank (4a) at the beginning of the second shoulder and cutting the blade (llb).
) is formed, and finally a plate (lln) is formed as shown in (d).

In the second processing process, as shown in Figure (C), a stepped part of the electrode ('') with a thickness of t and t2 was formed, so that very small processed chips were generated from the blank (4a). , and point C is the blade (lla).

(11, c) A blade (1, ib) is formed by performing stable electrical discharge machining without interfering with the surface, and the following machining is performed at the mouth of 2 under the same machining conditions. (d) The blade shown in Fig. The processing ends with the formation of (+, In).

Effects of Light 1 and 1 As explained above, according to the present invention, the turbine blades supported by the indexing device are indexed by rotating every two pitches of the blade, and the stages are indexed at each side position. By performing electric discharge machining using a pair of electrodes that form a single part, it is possible to minimize the size of the machining chips generated during machining, and the machining time is reduced because it is only necessary to machining the entire plate once with one type of electrode. This has the effect of shortening the time and ensuring reliable automated driving.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are front and side views showing the shape of the electrode part used to carry out the electrical discharge machining method according to the present invention, and FIGS. 2(a) to (d) are according to the present invention. An explanatory diagram of the machining process of a turbine blade, Fig. 3 is a schematic diagram showing a normal electric discharge machining device for turbine blades, and Figs. 4 (a) to (C) are explanatory diagrams showing the shapes and names of each part of the turbine blade. , FIGS. 5(a) and 5(b) are front and side views showing the shape of a conventional turbine blade machining electrode, and FIGS. 6 and 7(a) to 7(f) are conventional turbine blades. It is an explanatory diagram of the processing process. In the figure, (1) is an electrode, (2) is a holder, (4) is a holder, (5) is an indexing device, (11) is a blade, and (13) is an indexing device.
) is the wing bottom height line, and (14) is the same width as the wing tip. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] An indexing device that supports a material such as a turbine blade and rotates the material at an equal angle to determine the processing position, and an indexing device that supports a material such as a turbine blade and rotates the material at an equal angle to determine the processing position, and an indexing device that supports a material such as a turbine blade, etc. and an electrode section consisting of a pair of electrodes having a stepped section with a defined shape, the indexing device indexes the turbine blade or the like every two pitches, and the material is processed by the electrode section. electrical discharge machining method.